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Yayın Deterministic local doubling of W states(OSA - The Optical Society, 2016-11-01) Yeşilyurt, Can; Buğu, Sinan; Özaydın, Fatih; Altıntaş, Azmi Ali; Tame, Mark S.; Yang, Lan; Özdemir, Şahin KayaIn large quantum systems, multipartite entanglement can be found in many inequivalent classes. Preparing states of arbitrary size in different classes is important for performing a wide range of quantum protocols. W states, in particular, constitute a class with a variety of quantum networking protocols. However, all known schemes for preparing polarization encoded photonic W states are probabilistic, with resource requirements increasing at least sub-exponentially. We propose a deterministic scheme for preparing W states of size of any power of 2, which requires no prior entanglement and can be performed locally. We introduce an all-optical setup that can efficiently double the size of W states of arbitrary size. Our scheme advances the use of W states in real-world quantum networks and could be extended to other physical systems.Yayın Constructing quantum logic gates using q-deformed harmonic oscillator algebras(Springer, 2014-04) Altıntaş, Azmi Ali; Özaydın, Fatih; Yeşilyurt, Can; Buğu, Sinan; Arık, MetinWe study two-level q-deformed angular momentum states, and using q-deformed harmonic oscillators, we provide a framework for constructing qubits and quantum gates. We also present the construction of some basic one-qubit and two-qubit quantum logic gates.Yayın A novel approach to the systematization of alpha-decaying nuclei, based on shell structures(Springer, 2016-05-24) Yarman, Nuh Tolga; Zaim, Nimet; Susam, Lidya Amon; Kholmetskii, Alexander; Arık, Metin; Altıntaş, Azmi Ali; Özaydın, FatihWe provide a novel systematization of alpha-decaying nuclei, starting with the classically adopted mechanism. The decay half-life of an alpha-disintegrating nucleus is framed, supposing that i) the alpha-particle is born inside the parent, then ii) it keeps on hitting the barrier, while it runs back and forth inside the parent, and hitting each time the barrier, and iii) it finally tunnels through the barrier. One can, knowing the decay half-life, consider the probability that the alpha-particle is born within the parent, before it is emitted, as a parameter. Under all circumstances, the decay appears to be governed by the shell structure of the given nucleus. Our approach well allows to incorporate (not only even-even nuclei, but) all nuclei, decaying via throwing an alpha particle. Though herein, we limit ourselves with just even-even nuclei, in the aim of comparing our results with the existing Geiger-Nuttal results.Yayın Parameter estimation with Dzyaloshinskii–Moriya interaction under external magnetic fields(Springer, 2020-02-01) Özaydın, Fatih; Altıntaş, Azmi AliWe study the effects of external magnetic fields on the precision of parameter estimation with thermal entanglement of two spins in XX model, in the presence of Dzyaloshinskii–Moriya (DM) interaction. Although DM interaction excites but external magnetic fields usually decrease quantum mechanical properties of spin systems such as entanglement, we show by calculating the quantum Fisher information that not only DM interaction D but also homogeneous magnetic field B can increase the precision of parameter estimation, overwhelming the destructive effects of thermalization. We also show that inhomogeneous magnetic field b increases (decreases) the precision of parameter estimation if it is less (greater) than D. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.Yayın Prisoners’ dilemma in a spatially separated system based on spin–photon interactions(MDPI, 2022-09) Altıntaş, Azmi Ali; Özaydın, Fatih; Bayındır, Cihan; Bayrakçı, VeyselHaving access to ideal quantum mechanical resources, the prisoners’ dilemma can be ceased. Here, we propose a distributed quantum circuit to allow spatially separated prisoners to play the prisoners’ dilemma game. Decomposing the circuit into controlled-Z and single-qubit gates only, we design a corresponding spin–photon-interaction-based physical setup within the reach of current technology. In our setup, spins are considered to be the players’ logical qubits, which can be realized via nitrogen-vacancy centers in diamond or quantum dots coupled to optical cavities, and the game is played via a flying photon realizing logic operations by interacting with the spatially separated optical cavities to which the spin qubits are coupled. We also analyze the effect of the imperfect realization of two-qubit gates on the game, and discuss the revival of the dilemma and the emergence of new Nash equilibria.Yayın Engineering four-qubit fuel states for protecting quantum thermalization machine from decoherence(Multidisciplinary Digital Publishing Institute (MDPI), 2024-01-10) Özaydın, Fatih; Sarkar, Ramita; Bayrakçı, Veysel; Bayındır, Cihan; Altıntaş, Azmi Ali; Müstecaplıoğlu, Özgür E.Decoherence is a major issue in quantum information processing, degrading the performance of tasks or even precluding them. Quantum error-correcting codes, creating decoherence-free subspaces, and the quantum Zeno effect are among the major means for protecting quantum systems from decoherence. Increasing the number of qubits of a quantum system to be utilized in a quantum information task as a resource expands the quantum state space. This creates the opportunity to engineer the quantum state of the system in a way that improves the performance of the task and even to protect the system against decoherence. Here, we consider a quantum thermalization machine and four-qubit atomic states as its resource. Taking into account the realistic conditions such as cavity loss and atomic decoherence due to ambient temperature, we design a quantum state for the atomic resource as a classical mixture of Dicke and W states. We show that using the mixture probability as the control parameter, the negative effects of the inevitable decoherence on the machine performance almost vanish. Our work paves the way for optimizing resource systems consisting of a higher number of atoms.Yayın Superactivating bound entanglement in quantum networks via quantum Zeno dynamics and a novel algorithm for optimized Zeno evolution(MDPI, 2023-01) Özaydın, Fatih; Bayrakçı, Veysel; Altıntaş, Azmi Ali; Bayındır, CihanAn arbitrary amount of entanglement shared among nodes of a quantum network might be nondistillable if the nodes lack the information on the entangled Bell pairs they share. Making such a system distillable, which is called the superactivation of bound entanglement (BE), was shown to be possible through systematic quantum teleportation between the nodes, requiring the implementation of controlled-gates scaling with the number of nodes. In this work, we show in two scenarios that the superactivation of BE is possible if nodes implement the proposed local quantum Zeno strategies based on only single qubit rotations and simple threshold measurements. In the first scenario we consider, we obtain a two-qubit distillable entanglement system as in the original superactivation proposal. In the second scenario, we show that superactivation can be achieved among the entire network of eight qubits in five nodes. In addition to obtaining all-particle distillable entanglement, the overall entanglement of the system in terms of the sum of bipartite cuts is increased. We also design a general algorithm with variable greediness for optimizing the QZD evolution tasks. Implementing our algorithm for the second scenario, we show that a significant improvement can be obtained by driving the initial BE system into a maximally entangled state. We believe our work contributes to quantum technologies from both practical and fundamental perspectives bridging nonlocality, bound entanglement and the quantum Zeno dynamics among a quantum network.
